Abstract: The purpose of this instrumental case study (Stake, 1995) was to understand (a) the impact of human resource capital on ethnic minority middle school students' engagement in a mathematics community of practice and (b) the impact of this engagement on their mathematics identities. Case study methodology was used to collect data from nine participants. Qualitative data collection methods were used, including observations, audio taped individual and focus group interviews of participants, participants' responses to mathematics scenarios and a thorough examination of weekly journal logs kept by the participants. Data were analyzed using Creswell's (2003) content analysis coding procedures. The two themes that emerged from analysis of the data were sociocultural capital and personal capital. Sociocultural capital of the participants was demonstrated through their interactions as a mathematics community of learners including collaboration with peers, communication with peers, and the sense of community the participants perceived within the mathematics classroom [community of practice]. Other indicators of sociocultural capital in this study were participants' social networks with their peers and family members as well as their views of the relevance of mathematics in extracurricular activities and mathematics-related careers. Participants' personal capital was demonstrated by their intrinsic motivation, including factors of self motivation and self regulation; and by participants' extrinsic motivation, which includes the expectations of participants' families, participants' individual career goals and their prior knowledge and experiences. Implications for relevant classroom practices and further research are recommended.